Ligand-Stabilized and Atomically Precise Gold Nanocluster Catalysis: A Case Study for Correlating Fundamental Electronic Properties with Catalysis

Authors

  • Dr. Jing Liu,

    1. Center for Advanced Microstructures and Devices (CAMD), Louisiana State University, Baton Rouge, LA 70806 (USA)
    2. Center for Atomic-Level Catalyst Design, 324, Cain Department of Chemical Engineering, Louisiana State University, 110 Chemical Engineering, South Stadium Road, Baton Rouge, LA 70803 (USA)
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  • Dr. Katla Sai Krishna,

    1. Center for Advanced Microstructures and Devices (CAMD), Louisiana State University, Baton Rouge, LA 70806 (USA)
    2. Center for Atomic-Level Catalyst Design, 324, Cain Department of Chemical Engineering, Louisiana State University, 110 Chemical Engineering, South Stadium Road, Baton Rouge, LA 70803 (USA)
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  • Dr. Yaroslav B. Losovyj,

    1. Center for Advanced Microstructures and Devices (CAMD), Louisiana State University, Baton Rouge, LA 70806 (USA)
    2. Center for Atomic-Level Catalyst Design, 324, Cain Department of Chemical Engineering, Louisiana State University, 110 Chemical Engineering, South Stadium Road, Baton Rouge, LA 70803 (USA)
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  • Dr. Soma Chattopadhyay,

    1. CSRRI-IIT, MRCAT, Sector 10, Bldg 433B, Argonne National Laboratory, Lemont, IL 60439 (USA), Physics Department, Illinois Institute of Technology, Chicago, IL 60616 (USA)
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  • Dr. Natalia Lozova,

    1. Center for Advanced Microstructures and Devices (CAMD), Louisiana State University, Baton Rouge, LA 70806 (USA)
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  • Prof. Jeffrey T. Miller,

    1. CSE Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439-4837 (USA)
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  • Prof. James J. Spivey,

    1. Center for Atomic-Level Catalyst Design, 324, Cain Department of Chemical Engineering, Louisiana State University, 110 Chemical Engineering, South Stadium Road, Baton Rouge, LA 70803 (USA)
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  • Dr. Challa S. S. R. Kumar

    Corresponding author
    1. Center for Advanced Microstructures and Devices (CAMD), Louisiana State University, Baton Rouge, LA 70806 (USA)
    2. Center for Atomic-Level Catalyst Design, 324, Cain Department of Chemical Engineering, Louisiana State University, 110 Chemical Engineering, South Stadium Road, Baton Rouge, LA 70803 (USA)
    • Center for Advanced Microstructures and Devices (CAMD), Louisiana State University, Baton Rouge, LA 70806 (USA)

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Abstract

We present results from our investigations into correlating the styrene-oxidation catalysis of atomically precise mixed-ligand biicosahedral-structure [Au25(PPh3)10(SC12H25)5Cl2]2+ (Au25-bi) and thiol-stabilized icosahedral core–shell-structure [Au25(SCH2CH2Ph)18] (Au25-i) clusters with their electronic and atomic structure by using a combination of synchrotron radiation-based X-ray absorption fine-structure spectroscopy (XAFS) and ultraviolet photoemission spectroscopy (UPS). Compared to bulk Au, XAFS revealed low Au–Au coordination, Au[BOND]Au bond contraction and higher d-band vacancies in both the ligand-stabilized Au clusters. The ligands were found not only to act as colloidal stabilizers, but also as d-band electron acceptor for Au atoms. Au25-bi clusters have a higher first-shell Au coordination number than Au25-i, whereas Au25-bi and Au25-i clusters have the same number of Au atoms. The UPS revealed a trend of narrower d-band width, with apparent d-band spin–orbit splitting and higher binding energy of d-band center position for Au25-bi and Au25-i. We propose that the differences in their d-band unoccupied state population are likely to be responsible for differences in their catalytic activity and selectivity. The findings reported herein help to understand the catalysis of atomically precise ligand-stabilized metal clusters by correlating their atomic or electronic properties with catalytic activity.

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